Performance nutrition for ultra-marathon training and racing.
The recommendations within this blog come directly from the International Society of Sports Nutrition and this study: Tiller, N.B., Roberts, J.D., Beasley, L. et al. International Society of Sports Nutrition Position Stand: nutritional considerations for single-stage ultra-marathon training and racing. J Int Soc Sports Nutr16, 50 (2019). https://doi.org/10.1186/s12970-019-0312-9
Before we start, we are not nutritionists or sports dietitians. If you need sound, personalised advice we recommend seeking someone out experts in the nutrition and dietetics space.
What we can say is that now is a great time to be training your nutrition. What does this mean? Training your gut to be able to process calories during longer volume efforts (eg: long runs). If you plan on taking on board a specific amount of calories each hour during an event, you should be looking to train with that amount (or similar) during your long runs in training.
How many calories per hour should I be looking at?
For those of you who don't like reading studies or just want a ballpark figure to work off, the recommendations are as follows:
Events less than 50 miles (80km) = 150-300 cals/hr.
Events longer than 50 miles = 200-400 cals/hr.
That's a big range and in some respects can represent a huge amount of calories per hour, but it's important to note that some of your longer long runs can have you bridging the gap from one meal to another. It can be easy to think of your runs as something that exists in isolation, when in fact the energy expenditure across the entire day and week needs to be considered. Some of you may tolerate calorie volume better than others. That's where it's important to understand that we are individuals, so the recommendations above are for you to use as a guide and to then personalise. Beyond this, other factors such as the level of intensity you're operating at, environmental factors such as heat, cold and altitude, and elements such as fatigue play a huge role in the planning and execution of a nutrition plan during a run.
What does this mean practically? An important point to note is that different brands and sometimes different flavours within brands carry different caloric values. For longer events it's you may need to look to sources of real food to supplement your supplementary sports food intake. The best way to approach this practically is to use your long runs as a chance to experiment and refine. On your next long run keep all your gel and nutrition packets and tally up the totals after your run. This is an easy and simple way to track calorie consumption relative to exercise duration.
NB:
1g CHO = 4 cals
1g FAT = 9 cals
1g PRO = 4 cals
The best general advice we can give is you do you. People have different palates and enjoy different textures. Be wary about someone claiming a single source of calories as being the be all and end all. Try many things, prepare to be adaptable during long runs so you are able to be adaptable during long races. Find your absolute 'go to', then find a secondary source, then complement your first and second choices with a third source of calories. You may find on race day you end up mixing these in different orders and quantities or you may find yourself on a knee chugging from a 3 litre bottle of Coke when everything falls apart.
What about hydration? Taken from the same paper here: https://jissn.biomedcentral.com/.../10.../s12970-019-0312-9
Guidelines:
450-750ml/hr.
Again, this is a broad range and depends on the individual, temperature, intensity, altitude and other factors. The old "drink to thirst" approach that has been pushed for a number of years is not applicable to an ultra marathon setting as there are a number of factors that can influence thirst in multiple settings.
It's easy to dive down a rabbit hole when looking at things like sweat rate, weight loss and sodium, so the best thing you can do is make note of how you feel during and after your runs relative to the volume of fluid you've consumed. Some level of weight loss is normal and acceptable during races, weight gain is usually a sign of over-hydration.
What about sodium?
Guidelines:
500-700mg sodium/litre water.
The key electrolyte that allows fluid to move freely through the body is sodium. We are not trying to replace sodium; we are taking in sodium to work with our physiology under exercise stress conditions.
Consuming too much fluid with not enough sodium = hyponatremia.
How does this look practically?
Sodium rich sports drinks like Skratch, Nuun, Gu Hydration etc are infinitely better than products you'll find at the supermarket like Powerade and Gatorade which lack enough sodium while also containing dextrin and fructose which may cause GI distress. Salty broths and soups are also great sources of sodium during ultra marathons. You may also be taking salt on board through your choice of nutrition.
Salt tablets may not the best choice of sodium for some individuals as they can contribute to GI distress. Salt tablets can cause gut bacteria to be released which can onset diarrhea. A high concentration of sodium in the digestive tract causes water to be released to try and dilute the salt, rather than be absorbed into the blood where it is needed. As we mentioned above though, you are an individual and your long runs are your chance to experiment.